The present invention relates to a method for purifying silicone oil.
The present invention can be used, in particular, for silicone oil which is employed as electrical insulation and for cooling electrical high voltage devices. Such a silicone oil should be free of impurities so that the highest possible dielectric strength exists, e.g. greater than 60 kV/2.5 mm. In such use, almost unavoidable impurities have the result that, after a certain period of operation, the dielectric strength drops, e.g. to a value of about 15 kV/2.5 mm. Such impure silicone oil has the disadvantage that it results in operating malfunctions or even in destruction of the high voltage device in which it is used.
It is obviously possible to replace impure silicone oil with new silicone oil, from which merely the gases, e.g. air, dissolved therein have been removed, e.g. by heating at reduced atmospheric pressure (vacuum). Such a method is not cost effective and is therefore uneconomical.
As an alternative, attempts have been made to purify impure silicone oil by so-called vacuum distillation. Such purification is impeded in an uneconomical manner or even prevented by extensive foam formation.